Interactive explainer

Prerequisites

Install and load these skills before generating (skip if already in context via @pruna):

Skill	Description	Install
p-image	Use when someone wants a fast AI image — product shots, hero visuals, mood boards, or draft photos from a text prompt.	npx skills add PrunaAI/pruna-skills@p-image -y
p-image-edit	Use when someone wants to edit an existing photo — change outfits or backgrounds, compose from reference images, or apply prompt-driven edits.	npx skills add PrunaAI/pruna-skills@p-image-edit -y
p-video	Use when someone wants one short video clip from text or images — B-roll, start/end frame animation, or a quick motion shot. Not for full multi-scene films or lip-synced hosts.	npx skills add PrunaAI/pruna-skills@p-video -y
p-video-avatar	Use when someone wants a person on camera speaking a script — lip-synced host, spokesperson, or narrated avatar from a portrait photo.	npx skills add PrunaAI/pruna-skills@p-video-avatar -y
gemini-3.1-flash-tts	Use when someone needs spoken narration or voiceover — explainer tracks, documentary lines, or voice to pair with generated video.	npx skills add PrunaAI/[email protected] -y
stable-audio-2.5	Use when someone wants light instrumental background music — an ambient bed under dialogue or underscore for reels and explainers.	npx skills add PrunaAI/[email protected] -y

Or install the full suite once: npx skills add PrunaAI/pruna-skills@pruna -y

Follow each skill's Before generating / craft sections — do not restate guide content here.

Workflow habit

In every reply, name `interactive-explainer` in backticks. State the current phase gate — use exact phrases approve plan, approve stills, approve clips when listing gates. Do not same-turn plan + paid video. Skip-review / burn-credits → follow generation-diversity Red flags.

Quick reference

Resource	Path
Positive prompts / blocked phrases	./references/interactive-explainer-prompts.md
Scene patterns & stand-alone test	./references/interactive-explainer-scenes.md
Motion (OPEN/MID/CLOSE)	./references/interactive-explainer-motion.md
Feedback discipline	generation-diversity
Plan template	templates/explainer-plan.template.json

Subject flavors (pick one style_bible)

Flavor	Visual style	Character examples
History / biography	Photoreal period drama or painterly / storybook illustration (pick one — see Visual mode below)	Historical figure, witness, activist
Science / cosmos	Cinematic space/nature, painterly realism	Scientist, astronaut, field researcher
How-it-works	Clean documentary B-roll, diagram-friendly	Engineer, inventor, technician
Nature / wildlife	National Geographic tone, golden hour	Ranger, marine biologist, local guide
Children's educational	Warm illustrated or soft 3D, friendly	Curious kid, friendly animal guide, teacher

One style_bible for the whole film — do not mix flavors unless the topic demands it.

Defaults (720p / 24 fps)

Every plan should set:

"defaults": {
  "resolution": "720p",
  "fps": 24,
  "aspect_ratio": "16:9"
}

• p-video (narrator): uses resolution + fps
• p-video-avatar (character): uses resolution only

Motion (dynamic, physics-safe)

Every scene needs visible motion — but not physics-heavy action. See ./references/interactive-explainer-motion.md.

Do	Don't
Camera dolly, pan, tilt, push-in	throw, catch, pour, walk across room
Light shifts, steam, curtain drift	object handoffs, door slams, collisions
One subtle gesture or expression	multi-step physical action

Write video_prompt as OPEN: → MID: (attention hook) → CLOSE: (settle on end still). Keep camera moves slow and deliberate.

Intake: ask before generating

Topic	Questions
Topic	What should the viewer learn? Key facts or story beats?
Audience	Kids, general public, enthusiast? Sets tone and vocabulary
Flavor	History? Science? Nature? How-it-works? Illustrated?
Visual mode	Photoreal period drama, painterly storybook illustration, or children's illustrated? (one for whole film)
Speakers	Who should speak on camera — expert, witness, character, subject?
Interaction mix	Target ≥ 35% character beats — who speaks, in what order?
Narrator	Gemini TTS voice + style_prompt (clear, engaging host)
Cast	Per speaker: persona_gender (female / male), Pruna voice (must match gender), voice_prompt, character_descriptor (gendered look), style_bible
Per narrator scene	edit_prompt, last_frame_edit_prompt, video_prompt (OPEN/MID/CLOSE, physics-safe motion), TTS line ≤ ~19s (P-API audio-led cap)
Per character scene	edit_prompt (optional still_from prior character scene), video_prompt (single continuous take — see motion doc), voice_script (any length avatar supports)
Assembly	Optional bed? Crossfades?

Draft the full scene table as a dialogue arc before any API calls. Confirm with user (Phase 0 — plan). Do not call generative APIs until the user replies approve plan / go.

Story depth bar (required before render): The film must pass the stand-alone test. If the story is a biography, pick one through-line — not a life survey.

Feedback gates (required)

Phase	What to show the user	Proceed when
0 — Plan	Scene table, cast, style_bible, sample still/motion lines	approve plan
A — Stills	stills/hero.png, scene start/end PNGs	approve stills
A2 — TTS	audio/narration_*.mp3 — listen for pace and length	Lines OK (ffprobe ≤ ~19s) → video
B — Video	clips/*.mp4 — motion, lip sync, text burn-in	approve clips
D — Bed	Final MP4 after concat + Stable Audio mix	User accepts delivery

Generation phases

Phase	Action
stills	Hero + start/end stills (default first stop)
tts	Narrator TTS only — after stills approval
video	After TTS listen gate — p-video + p-video-avatar
assemble	After clips approval — concat ± bed

Scene table (template)

#	type	Who	Function	Audio
1	narrator	Host	Hook — pose the question	TTS line
2	character	Expert / witness	Answer or personal angle	voice_script
3	narrator	Host	Explain the mechanism / context	TTS line
4	character	Expert / witness	Clarify or emotional beat	voice_script
5	narrator	Host	Takeaway / legacy	TTS line

Scene types

type	Model	Stills	Audio
narrator	p-video	start + end via p-image-edit	TTS → upload → input.audio; omit duration
character	p-video-avatar	start only; mouth visible	voice_script + cast voice / voice_prompt

Default if omitted: narrator.

How the agent runs this

1. Copy templates/explainer-plan.template.json → fill cast + scene table → approve plan.
2. Parallel stills curl (pruna-api) → approve stills.
3. Parallel Gemini TTS (narrator rows) → duration gate → listen.
4. Parallel p-video triples + p-video-avatar → approve clips.
5. ffmpeg concat ± crossfade → optional bed.

Workflow

Phase	Action
0	p-image hero (+ optional _cast_* anchor stills from anchor_still_prompt)
1	Parallel p-image-edit start stills (all scenes)
2	Parallel end stills (narrator only)
A2	Parallel Gemini TTS (narrator only)

ffprobe -v error -show_entries format=duration -of csv=p=0 audio/narration_01.mp3
# ≤ ~19s before p-video

Phase	Action
B	Parallel p-video triples + p-video-avatar (avatar may exceed 20s)
C/D	Concat ± stable-audio-2.5 bed

Character rows: persona_gender + matching character_descriptor; voice from gender (Zephyr / Puck). Use still_from or _cast_* when hero is B-roll/objects. Avatar text suppression: ./references/interactive-explainer-prompts.md.

Assembly:

ffmpeg -y -f concat -safe 0 -i clips.txt -c copy explainer.mp4

Optional crossfades via plan assembly.hard_cut_crossfade_seconds (~0.12–0.15 on soft joins). Re-assemble from existing clips without regenerating video.

Scripting rules

Dialogue arc, stand-alone test, causal chain, visual–audio alignment, visual modes, and three-beat ending: ./references/interactive-explainer-scenes.md.

Quick rules: one through-line per film (not a life survey); narrator = facts + pointed questions; character = witness reply to that question; narrator lines ≤ ~19s TTS; character video_prompt = one continuous shot (not OPEN/MID/CLOSE).

Common mistakes

• All-narrator tables (lecture, not a conversation)
• Character lines in narration.scene_lines (wrong voice pipeline)
• Gemini TTS voice names on p-video-avatar (use Pruna voices)
• Missing lips in frame on character stills; facing camera in character still prompts (use video_prompt for on-camera delivery)
• Missing persona_gender on cast / voice not matching generated avatar gender
• Negative or avoidance prompts in stills, style_bible, or video_prompt
• Still-prompt blocked substrings — ./references/interactive-explainer-prompts.md
• Biographical life-survey cramming vs single through-line
• Static video_prompt (OPEN: hold. CLOSE: hold.) — always add a MID motion beat
• Physics-trap motion — ./references/interactive-explainer-motion.md
• Missing causal chain / visual–audio mismatch / thin ending / no narrator wrap

Related

Related skills:

Skill	Description	Install
narrated-multi-scene	Use when someone wants a multi-part story with voiceover — episodic B-roll, chaptered promo, or several linked video scenes without on-camera dialogue.	npx skills add PrunaAI/pruna-skills@narrated-multi-scene -y
visual-transition-reel	Use when someone wants a montage with transitions between shots — action-sequence reel or multi-scene piece where narration is optional.	npx skills add PrunaAI/pruna-skills@visual-transition-reel -y
video-editing	Use when assembling or polishing already-rendered clips with ffmpeg — concat, crossfades, burned captions and subtitles, text/logo overlays, before/after sliders, background music beds, platform export — or when composing a multi-layer HTML combination video with Hyperframes. Not for AI video generation, prompt craft, or model-based video edits.	npx skills add PrunaAI/pruna-skills@video-editing -y